In the late 1960's all of GM's Divisions (Chevy, Pontiac, Olds, Buick and Cadillac) were using the Rochester Quadrajet. Demand was so high that Rochester Products could not supply enough carburetors. GM's solution was to have the Carter Corporation also manufacture Quadrajet Carburetors.
You can identify a Carter Q-Jet by the cast in "MFG by Carter Carburetor for GMC" on the driver side of the carburetor. Carter produced Quadrajets for GM for several years, other than the Carter name they are basically the same as a Rochester Quadrajet and use the exact same service parts.
Below is a list of Tech articles with the most recent ones listed first.